Range-finder.



G. GRIFFITH.

RANGE FINDER.

APPLICATION FILED NOV. 4. 1911.

Patented Aug. 31, 1915,

3 'SHEETSSHEET I.

Elk/Q E INVENTOR.

I gy M ATTORNEY.

G. GRIFFITH. RANGE FINDER.

APPLICATION FILED NOV. 4. I911. LWQJHI Patented Aug. 31,1915.

3 SHEETS-SHEET 2.

INVENTOR. ymy m ATTORNEY.

I WITNESSES MV %A 5 e. GRIFFITH.

RANGE FINDER.

APPLICATION FILED NOV. 4. Hill.

3 SHEETSSHEET 3.

ATTORNEY Patented Aug. 31, 1915.

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' enavns GRIFFITH, OF SAN rnaucrsco, camromrm.

RANGE-FINDER.

Specification of Letters Patent.

Patented Au 311, late.

- To all whom it may concern:

,Be it known that I, GRAVES GRIFFITH, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented new and useful Improvements in Range-Finders, of which the following is a specification.

This invention relates to range finders and more particularly to that type known in the art as constant angle variable base finders and which are adapted to be used in maritime service, civil engineering and other fields wherein it is desired to ascertain the distance: of an object from the llttt .nection thereof with the bar.

observer without requiring any calculation.

One ofthe principal objects of theinvention is to" improve upon the structure as shown and described in my Patent #959,338

bearing date of May24, 1910, and in which the separate systems of prisms are arranged to refract the object rays at right angles to each other and then in parallel planes through the object glass and to the eye piece.

Further objects of the invention will appear as the following specific description 1s -read in connection with the accompanying drawings, which form a part of this application, and in which I Figure 1 is a top plan vi removed and with the optical parts made large in proportion to the instrument for the sake of plain illustration. Fig. 2 is a diagrammatic view showing the optical parts in section. Fig. 3.is a section on the line A- A of Fig. 1. Fig. 4 is a similar section on theline BB of Fig. 1. Fig. 5 is an end view with parts broken away and parts omitted. Fig. 6 is a vertical section taken on the line (3-4] of Fig. 1. Fig. 7 is a rear elevation of the standard showing the con- Fig. 8 is a section through the center of the machine.

' Fig. 9 is a detail horizontal section on the line EE of Fig. 8. Fig. 10 is a diagram illustrating the mathematical principle governing the operation of the device. Fig. 11 isa perspective diagram showing the lines of reflection or refraction of the object rays to the eye of the observer. Fig. 12 is a sectional view through a modifiedform of instrument. V j I Referring more particularly to thefdrawings, A represents a suitable base which is flanged at the bottom thereof and is preferably in' the form of the frustum of-a cone with its head provided with adepending ew with the cover bearing in which the spindle B of the I mounting head B is placed for rotation. The head of the base is provided with circu lar rack teeth 1 which are engaged by a pinion B carried upon the end of a stub shaft journaled in the head B and operated by a knurled button 2. By rotating this button the head B will be rotated for the azimuth motion. A suitable locking screw 3 is adapted to secure the head against rotatlon. Extending vertically from the head are a pair of parallel standards B between which is pivoted a plate B havm an arc-shaped toothed segment B upon its lower end which is adapted to be engaged by a worm wheel B carried at the end of the shaftwhich is operated by the knurled button B. In this manner 'it will be hereinafter understood that the instrument may be tilted in a vertical plane for any suitable purpose.

The plate B has pivoted thereto a bar C by means of the ears G which are carried ary double reflecting prisms P and P respectively. The center of the bar has projecting forwardly thereof a frame 6 in which the objective 0 dis mounted, while immediately in the rear of the objective 0 is mounted the oppositely arranged and double reflecting prism or prisms P.

Mounted in suitable channels formed in the bar are rack members R, R which have their free ends connected to frames F, P mounted to slide upon the bar C, each being provided with a dovetailed recess to engage the dovetailed portion or guide member upon the bar, as shown. These rack bars are each engaged by a pinion F which is operated through a button shaft F projecting back of the bar in position for the operator to grasp. The rack R is connected to the frame P while the rack R is connected to the frame P and each of there frames carries double reflecting prisms which may be ofthe angular typeshown in Fig. 11, or any other type desired. These prisms car-' ried bythe frame P and P are adaptedto be moved toward and away from each other by the operation of the pinion F and the lower rack bar R carries a transparent scale S which operates across a suitable'bisecting member I, such as a vertical cross hair or the like. Immediately behind the cross hair I is an eye piece G which extends through the casing and is arranged in such a manner as to take in the cross hair, the scale S and the images which will be bisected by the cross hair and reflected into the eye piece by the prisms P It will be noticed that the objective 0 is constructed of a double convex lens and a piano-concave lens which, is'divided into half, one half being arranged upon one side of the double convex and the other upon the opposite side and in another plane and also that the lenses in the frame P are arranged in different planes.

In practice, when the instrument, is focused'upon an object, one ray is reflected by the prism P through the upper half of the objective 0' over the prism P and is then double reflected by the prism P tothe upper half of the prism P and to the eye of the observer through the eye piece Gr. The other ray is reflected by the prism P through the lower half of the objective 0 beneath the prism P and is then double reflected by the prism P to the lower half of the prism P which is arranged in opposition to the upper half thereof and hence to the eye of the observer through the eye piece G. It will be noticed from the inspection of Figs. 1 and 12 that the rays from the object diverge to the prisms P, P and then are reflected or. refracted in parallel planes to the prisms P, P and thence to the prisms P and to the eye piece. Both objects, that is the one reflected by the prism P and the one reflected by the prism P are bisected upon the cross wire I. The bar 0 is covered with a casing E having an opening E therein through which the rays from the object pass to the prisms. Itwill be clearly understood that the prisms P, P may be right angular, as shown in Fig. 11, instead of as shown in Fig. 1 where they are double reflectedor refracted in the same direction as the prisms shown in Fig. 11, and that one of these prisms may be held stationary while the other is moved toward and away from the angles to the object while the other prism may reflect the ray at an acute angle to the body. In either instance the reflected rays extend in parallel lines, one to the other from the point of reception by the instrument to the eye piece.

In the modification shown in Fig. 12, the preferable form of the device is illustrated. In this the ears C pass through the outer casing E which is circular and are connected to a bar C which is tubular, as'shown.

The lower portion of the bar is provided with a dovetail groove upon its inside and slidably mounted therein is a dovetaiLportion carrying the frames P, P of the movable lenses. These frames are connected to the rack bars R, R, as is usual, and are movable toward and away from each other, the direct. rays being received upon the prisms carried by the frames throughthe opening E in the outer casing and through a similar opening in the bar C. The objective O is carried upon the frame which is rigid with thetube and. is constructed to carry the prisms P. Suitable frames are secured to the ends of the tube and carry the prisms P P. In this figure, the prisms P, P are only shown, the prisms P P being at the opposite end of the instrument and therefore incapable of illustration in such a figure.

\Vhen it is desired to secure more light upon the scale than that which comes through the prisms, the bulls eye and prism J and J are arranged in an opening formed in the bottom of the bar and adapted to reflect the light rays received through the bulls eye directly upon the scale.

Having thus describedthe invention, what I claim as new is 1. A range finder comprising image receiving prisms located in different planes at the opposite sides of a point located between the ends of a base line, a lens located intermediate the said image receiving prisms, reflectors located at the ends of the base line, 100 the reflector at one end of the base cooperating with the image receiving prisms beyond the other side of the said point located between the ends of the base line, an image uniting prism located approximately at said 105 intermediate point of the base line and means for varying the distance between the said image receiving prisms.

2. A range finder comprising image receiving prisms located in different planes at 110 the opposite sides of a point located between the ends of a base line, a lens located intermediate the said image receiving prisms, reflectors located at the ends of the base line, the reflector at one end of the base line cooperating with the image receiving prism beyond the other side of the said point located between the ends of the base line, an image uniting prism located approximately at said intermediate point of the base line, and means for simultaneously moving said image receiving prisms to vary the distance between them.

3. A range finder comprising image receiving prisms located at the opposite sides 126 of a point located between the ends of a base line, a lens located intermediate the said image receiving prisms, reflectors located at the ends of the base line, the reflectorat one end of the base line cooperating with 130 nearer the image receiving prism beyond theother side of the said point located between the ends of the base line, an image uniting prism located approximately at said intermediate point of the base line, means for varying the distance between the said image receiving prisms, a bisecting line fixed with relation to the base line and a scale movable with one of the image receiving prisms and disposed transversely of the said bisecting line.

4:. A range finder comprising image receiving prisms located at the opposite sides of a point between the ends of a base line, a single lens located intermediate the said image receiving prisms and cooperating with both of said prisms, reflectors located at the ends of the base line, the reflector at one end of the base line cooperating with the image receiving prism beyond the other side of the said point located between the ends of the base line, and an image uniting prism located approximately at said intermediate point of the base line.

In testimony whereof 1i aflix my signature in presence of two witnesses.

GRAVES GRIFFITH. 

